The Surrogate
by Chanticleer Hegemony
Summary: Wiggle.
1. Chapter 1

" _That's, uh… quite an urban renewal program they've got going over there."_

\- Godzilla 1985

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Destruction swarmed through Fuyuki faster than the evil demon worms swarming in Rin's uterus. Most of the hive still retained Sakura as their queen, but more than a fair number of the small creatures had moved on to start a second colony in her sister's ripe, magic-fueled body. White-haired Sakura was in another corner of the city carving out her own fiery domain. Nothing stood in the way of the mutated twins of terror.

Civilians fled for their lives in Rin's wake. Holding out her open palm, she summoned hundreds of weapons—floating swords with blades wrapped in poisonous silver serpents—and sent them forth to impale their defenseless targets. An enormous pentagram appeared under her feet, sending out waves of negative energy that caused the buildings at her sides to spontaneously erupt like volcanoes.

If Rin's endless psychotic laughter wasn't enough to send her enemies shivering in fear, the glare of her zombified eyes and the black veins on her face would get the job done. She was the stark example of a magus gone out of control; Death in a miniskirt, red turtleneck, and thigh high stockings. As she glanced back and forth looking for the next thing that could sate her chaotic appetite, her black twintails moved like two oversized slugs flailing on the sides of her head. She placed a hand on her flat stomach and smiled as she felt the thousands of tinier slugs that flailed below.

Two figures came out of the fire. Shirou and Saber both had solemn expressions, but they were determined to save the world at any cost. Rin snickered at her challengers and gathered her cataclysmic powers.


	2. The Dendrobium Effect

_**Tsundere:** A Japanese term for a character development process that describes a person who is initially cold and even hostile towards another person before gradually showing their warm side over time._

\- Wikipedia

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Archer and Rin stood together before the quivering legions of Sakura Matou. The two were inseparable. Nothing could stop them.

And then an abyss of Lovecraftian horrors opened underneath Archer's feet and swallowed him.

Archer was devoured whole as the earth hungrily closed over him, never to be seen again. Rin reached out and screamed his name from the edge of the ravine. Sakura watched with a sinister grin, delighted by Rin's misery. Then there was silence.

Rin shot a vengeful glare toward her sister. She rushed at Sakura with a series of attacks involving Chinese kenpo and jewels, but Sakura blocked each hit by casually waving her hand and conjuring magic barriers around herself. Releasing a burst of Crest energy, she sent Rin hurtling backward and crashing face-first into the street.

The pavement changed colors as a large pentagram appeared underneath Rin. The points of the magic circle formed the constellation of a woman lovingly entwined with a giant serpent.

Rin shook her head and painfully lifted herself onto all fours. Confused by the pentagram, she looked over her shoulder toward her sister.

"What the hell is this, Sakura?" Rin shouted. "Stop playing around!"

"'Hell' might be the best word for it," Sakura answered in a threatening voice.

A nest of massive black earthworms burst out of the asphalt underneath Rin and pulled her into the air. Two of them wound around her arms. One wrapped itself over her neck like a slime-covered scarf. Most of them targeted her flailing legs. Smaller versions of the same creatures materialized from the trail of Sakura's dress, slithered up the backs of the larger worms, and crawled over Rin's body. Sakura waved her hand and flexed her fingers, controlling the swarm with invisible puppet strings.

Zouken venom was part sedative and part aphrodisiac. A few loose droplets on her hands and neck was all it took before Rin started to feel the effects. She was stubborn, but she was gradually losing the fight.

Sakura pinched her thumbs and forefingers together and made a motion like she was opening a present. Something ripped underneath Rin's black miniskirt. The worms tossed her panties aside as worthless rubbish.

The creatures tangled around Rin's legs, covering from her shoes to her waist. The entire collective began to quiver and churn as it slowly took on a familiar shape. The eyes. The nose. The mouth. The sunken elderly features. In a matter of seconds, it was all there.

The worms had molded themselves together in the grotesque likeness of Zouken Matou's face. The top half of Rin was growing out of his forehead.

Rin couldn't see any of the devilish things happening inside of the Zouken monster, but she felt the ovipositor emerging between her wrapped legs and sliding gently into her. She gasped in shock while a deep red blush appeared on her cheeks.

The Scylla Formation was complete. Two had become one. The gateway was open. Sakura finished the incantation for Unlimited Crest Works by forming her middle and index fingers into a "V" shape and flicking her tongue between the gap.

An army of thriving demon worms became buddies with Rin's uterine wall. Rin let out a good scream, a passionate scream, as her humanity instantly gave way to carnal impulses. Her top half tiredly slumped forward while the Zouken hive ruthlessly held the rest of her in place.

Some of the tendrils gathered like a bridge under Sakura's bare feet and carefully elevated her so she could be on the same level as her sister. When she was close enough, Sakura tenderly pet Rin on the cheek.

"Have you had enough yet?" Sakura asked mercifully.

"Ye-… yes…" Rin panted feverishly. The tip of her tongue slipped over her bottom lip.

"Do you still want to fight me?" Sakura asked.

The worms keeping Rin secured in place shifted slightly, causing her to suddenly yelp. The only amount of modesty she had was the thick black tendrils forming a blanket over the vile misdeeds happening below her waist.

"N-… no…" Rin said in embarrassment.

Sakura prodded her through her sweater, touching her on the stomach just above where the tendrils closed around her. The tiniest amount of pressure caused Rin to rock her head back and howl in maddening ecstasy.

"Looks like your Crest Capacity is at its limit," Sakura said playfully. "I thought you'd have more room since you're the bigger sister, but I guess your body can't take as much when it hasn't been prepared like mine."

She grasped Rin by the chin and looked into her desperate, lust-filled eyes.

"Now, what _do_ you want?"

"To… to… des-… destroy…" Rin whimpered.

Sakura let go of her sister. Rin bit her lip as the hidden ovipositor carefully retracted from underneath her tentacle-wrapped skirt. The Zouken abomination dissolved back into individual parasites and slowly lowered Rin and Sakura back to their feet. Rin took a few awkward steps on her numb legs before collapsing on her side. A stream of black slime slipped down the inside of her thigh and soaked into the nylon. Tiny black veins slowly erupted on the sides of her face, stretching over her cheeks like gnarled hands.

"Relax, Rin," Sakura said over her. "The Crest Worms will spread through your body and convert all of your Mana soon enough. Then you'll be ready to join me."

Rin twitched slightly as she let out a weak, uncontrollable giggle. Joyful tears grew in the corners of her sleeping eyelids.

Sakura left Rin to her well-deserved rest. As her bare feet silently walked across the pavement, her hips swayed in serpent-like waves with each step.


	3. Epilogue

The once mighty city had been reduced to smoldering concrete ruins. Rin lounged on a large piece of industrial rubble basking under the pitch black morning eclipse. Occasionally she would rest a hand over her stomach and cross her stocking-clad legs or shift her waist in a different direction, giving the impression of someone who was in a state of both extremely relaxation and mild discomfort. Mostly she just smiled at the hell's gate in the sky and slowly swung her ankles off the edge of the rubble, not like the Emerald Herald from Dark Souls II. The Wiggly Herald.

Unbridled mass murder took a lot out of Rin. On the plus side, replenishing her body's Mana supply hadn't always been this simple. Before she would have to meditate with Shirou or another magus just to make up for the resources she used in basic summoning spells. Now she could lay waste to entire cities overnight and she was completely self-reliant in her magica-regenerating ways. As long as you considered the millions of miniature demon-forms ceremonially bound to her southern depths to be a part of her self, of course.

The only outward symptoms of the infestation were the small inflamed veins on Rin's cheeks and a slightly corrupt tint in her eyes. If she were to lift up the loose fabric of her turtleneck, one may have been able to catch a glimpse of something small and unsightly flexing through her lean abdominals. Within the flesh, the crests squirmed and toiled every which way except _out_ , the one place they were strictly forbidden to go. The seal was good and strong, and Rin—in her sublime madness—planned on keeping it that way.

A ghastly woman with white hair strode out of the smoke in front of Rin. The skirt of her long black dress trailed after her, leaving an elegant streak of coagulated blood wherever she went. If Rin was Pestilence in a miniskirt and thigh highs, this was Death in an evening gown.

"Heheh. I knew I sensed your vile taint somewhere around here, elder sister," Sakura giggled. "How are the worms doing today?"

Rin slowly rolled her shoulders back, pushed her waist forward, and quietly exhaled. Her eyes narrowed into tiny half-dreaming slits. She traced the curled tips of her fingers through the cold cinders at her sides like a tamed kitten kneading her claws.

" _Restless_." The word flowed sensually from her lips.

"That's how it will always be," Sakura slowly nodded. She modestly crossed an arm over her waist and tucked her hand behind the opposing hip. "I learned to accept them in my training. Looks like you've learned to enjoy them."

Rin closed her eyes the rest of the way and offered her sibling a smirk.

"I should be on my way. I don't want to disturb your bliss," said Sakura. "I think I'll punish Tokyo next."

The two doom witches parted ways. Rin remained on her rock and swayed her head to the beat of an imaginary orchestra. Sakura left as eloquently as she arrived, leaving the blood of her countless victims behind her in a long red carpet.

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 _Author's note: I was drinking Crystal Pepsi and thinking about tumblr stuff when I was writing this._


End file.
